Tubular filter shell



Feb. 21, 1967 QFFER 3,305,161

TUBULAR FILTER SHELL Filed Sept. 29, 1964 INVENTOR. FaZcv'z'" J1 Offer United States Patent M 3,305,161 TUBULAR FILTER SHELL Robert J. Oifer, Racine, Wis., assignor to Walker Manufacturing Company, a corporation of Delaware Filed Sept. 29, 1964, Ser. No. 400,139 1 Claim. (Cl. 229-93) This invention relates to shells of flexible material, such as paper shells used as containers for automotive filter elements.

It is an object of this invention to provide a self-locking tab design which will permit a quick and effective assembly of opposite ends of a strip of flexible material which has been formed into a tube to provide a shell or container.

The invention accomplishes the foregoing and other objects by means of a tab construction in which the tabs are formed at one end of a flexible strip to project longitudinally from the end of the strip. The other end of the strip has slots formed in it adjacent the end and, on opposite sides of the slots, angled slits are formed and these define a cantilever resilient flap that will hold the tabs in place after they have been inserted in the slots.

The invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a broken layout of opposite ends of a flexible strip prior to insertion of the tabs in the slots;

FIG. 2 is a layout showing the tabs and slots just prior to connection;

FIG. 3 is a side elevation of a shell showing the tabs and slots in interlocked condition;

FIG. 4 is an end view showing the tubular nature of the shell that is formed after the tabs and slots are interlocked; and

FIG. 5 is an enlarged section on line 55 of FIG. 3.

The flexible material 1 may be a sheet of perforated stiff paper that is to be formed into a tubular shape or shell and then used as a housing or container for a filter element, such as a pleated paper oil filter commonly used in automotive internal combustion engines. It is desirable in such usage that the two ends 3 and 5 of the flexible material 1 be rapidly interconnected, either manually or by machine, and that this connection be foolproof in the sense that it will not accidentally become unlocked.

In accordance with the invention, a pluralty of tabs 7 are formed in the paper to project from the end 3. They V comprise a reduced width neck portion 9 and lateral shoulders 11 of enlarged head 13 which extend outwardly from the neck 9. The head portion 13 is preferably tapered on its forward end, as indicated at 15, to facilitate its entry into the slot 17 which is formed for each of the tabs 7 adjacent the end 5 of the flexible material 1. The slots 17 are preferably substantially wider than the'thickness of the paper or flexible material 1, preferably about 2 or 3 times the thickness of the paperto reduce production tolerances and increase ease of entry. Transversely, the length of the slots is less than the width of the heads 13 but greater than the width across the nar rowest portion of the tapered sections of the head so that they may easily enter the slots 17.

3,305,161 Patented Feb. 21, 1967 An important feature of the invention resides in the slits 19 which extend outwardly from the far corners of the slots 17, as can be clearly seen in the drawings. These slits extend at angles of preferably about 15 to the transverse length of the slots 17 and define cantilever flaps 21 which can lift slightly out of the plane of the flexible material 1 to permit the wide portions of the head 13- to slide through the slot and slits whereby the shoulders 11 are behind the back surface of the paper with the necks 9 extending through the slots 17. In this position the flaps 21 exert a pressure on the tabs tending to hold them in place and cause the shoulders 11 to catch the strip 23 between the slots 17 and the edge 5 to prevent accidental disconnection. The flaps 21 also help to hold the tabs and thus the end 3 of the material tightly against the face of the strip 23 since the strip is wider than the length of the necks.

I claim:

A locking means for interconnecting opposite ends of a flexible piece of material that is wrapped from a flattened sheet into a tubular form comprising a tab projecting from one end of the material and having a neck portion and a head portion, the'head portion being wider than the neck portion and defining a pair of shoulders, the head portion being tapered at its forward end, the other end of the material having a slot, said slot having a transverse length less than the maximum width of the head portion but greater than the width across the tapered portion and greater than the width of the neck, said slot having a width approximately twice as large as the thickness of the flexible material, said flexible material having slits extending from the two corners of said slot remote from said tab and extending at angles to the transverse length of the slot and forming a resilient flap including the entire length of one side of the slot, said tab extending through said slot, said flap lying in substantial ly the same plane as said slot when said flexible piece of material is in its flattened sheet form with the shoulders engaged on the surface of said flexible material opposite to the side of entry of the tab upon wrapping of said sheet into its tubular form, insertion of said tab through said slot being effective to resiliently displace said flap through cantilever deflection about its ends adjacent the ends of said slits, said cantilever deflection of resilient flap being effective to hold said tab in place so that the neck extends through said slot, said neck being shorter in length than the spacing of said slot from the end of the material whereby the two ends of the material overlap when said tab is inserted to hold the flexible piece of material against transverse displacement in one direction.

References Cited by the Examiner UNITED STATES PATENTS 1,178,748 4/1916 Nicholson 22921 1,991,746 2/1935 Hiatt 22921 X 3,037,684 6/1962 Andrews et al. 22939 X 3,208,478 9/1965 Baines 22939 X JOSEPH R. LECLAIR, Primary Examiner. DAVID M. BOCKENEK, Examiner. 

